There are three main types of fiberglass grating production processes: reciprocating fiber winding, continuous fiber winding, and centrifugal casting.
Reciprocating Fiber Winding (a fixed-length method): In this process, the impregnation tank reciprocates with a rotating mandrel. Long fiberglass filaments are laid at a certain angle relative to the mandrel axis. The winding angle is controlled by the ratio of the impregnation tank's moving speed to the mandrel's rotational speed. The translational movement of the impregnation tank is computerized electromechanical control. The number of winding layers gradually increases until the designed wall thickness is reached. After winding, the resin in the product is basically cured. After curing, the mandrel is removed from the fiberglass tube.
Continuous Fiber Winding (a continuous method): In this process, the tube moves through a feeding station that supplies a mixture of resin-impregnated untwisted roving, chopped fiberglass fibers, and resin sand. The tube is formed as the mandrel continuously advances.
Centrifugal casting process (a fixed-length method): In this process, cut glass fiber reinforcement and sand are fed into a steel mold fixed to a bearing. Unsaturated resin with a catalyst is injected into one end of the mold, impregnating the reinforcement. Under centrifugal force, the resin displaces air from the fibers and fillers, creating a dense, non-porous composite material. Due to the centrifugal force, a smooth, resin-rich inner surface layer forms on the inner wall of the pipe, which then cures at a higher temperature. Pipes manufactured using this method are also called fiberglass reinforced plastic (FRP) sand-filled pipes.
There are far more manufacturers worldwide using the reciprocating fiber winding process than those using the other two methods. One reason is that FRP pipes manufactured using this process have a wider range of applications and better applicability.
